The present invention relates in general to the art of apparatus for wrapping or banding palletized loads and, more particularly, to improved apparatus for placing corner protectors and/or top protectors onto a load prior to the wrapping or banding thereof.
The present application is a continuation-in-part of copending application Ser. No. 083,518 filed Jun. 30, 1993 disclosing apparatus for wrapping plastic film material around a stationary article or load, and the disclosure of which application is incorporated by reference herein. The improvements according to the present invention find particular utility in conjunction with apparatus of the character disclosed in the foregoing copending application and, accordingly, will be described herein in conjunction with such apparatus. At the same time, it will be appreciated that the improvements have utility in conjunction with other apparatus for packaging loads in plastic film material as well as apparatus by which loads are banded as opposed to being wrapped in plastic film material.
Load or article wrapping apparatus of the character to which the present invention relates generally comprises a stationary frame for receiving a load to be wrapped, and a rotating and vertically reciprocable film dispensing unit supported on the frame for rotation about the load to wrap the latter in the film. The load to be wrapped may, for example, be comprised of a plurality of square or rectangular articles placed side-by-side and end-to-end in a plurality of vertical layers, whereby the load has opposed pairs of opposite vertical sides, adjacent ones of which sides meet at an angle to provide a vertical corner therebetween. The load also has a top defined by horizontal top edges extending between the vertical corners. Prior to wrapping or banding the load, it is often desirable to apply corner protectors to the corners of the load and/or to apply a top protector to the top of the load so as to protect the vertical corners and top edges of the load from being crushed by the wrapping film or strapping, or being crushed or otherwise damaged during transportation and storage of the wrapped or strapped load.
The corner protectors are generally made from paper or paperboard material pre-folded to provide a pair of panels having inside surfaces meeting at an angle corresponding to that of the corners of the load. Generally, apparatus for applying corner protectors onto a load comprises, for each corner of the load, a magazine arrangement for storing a supply of the corner protectors, and a pick-up and transfer mechanism associated with the magazine for removing a corner protector from the magazine and transferring the protector to the corresponding corner of the load. One such apparatus heretofore proposed for the latter purpose is disclosed in U.S. Pat. No. 5,226,280 to Scherer et al wherein the magazine for the corner protectors is in the form of an inclined chute having an inner discharge end relative to the load and from which the corner protectors are withdrawn and transferred to the load. The corner protectors slide downwardly along the chute toward the discharge end under the influence of gravity and a wheeled feed carriage therebehind. The innermost corner protector is removed from the magazine and transferred to the corresponding load corner by an articulated arm assembly pivotal sequentially about two pivot axes to initially orient the corner protector relative to the corner. Thereafter, portions of the arm assembly are jogged horizontally in directions perpendicular to one another to move the protector into engagement with the corner of the load.
Apparatus of the foregoing character is structurally and operationally complex and, thus, expensive from the standpoint of cost of construction, maintenance and operating time. In this respect, for example, the magazine carriage has to be withdrawn and held at the upper end of the chute during loading thereof with corner protectors and then released to engage behind the outermost one of the corner protectors relative to the discharge end of the chute. Furthermore, while there is a restraint for engaging the innermost corner protector in the chute to preclude more than one corner protector being withdrawn at a time from the magazine, including a finger for engaging the upper end or the innermost corner protector, the mechanism for this purpose is structurally complex and there is a time during removal of a corner protector from the magazine when the finger provides the only restraint and fails to perform its function resulting in one or more of the corner protectors falling outwardly of the discharge end of the magazine. Particularly in this respect, the corner protectors are often recycled and intermixed with other protectors whereby, as the result of damaged ends or such intermixing the magazine is filled with protectors of different lengths. Thus, one or a number of "short" protectors reaching the innermost end of the magazine are not engaged by the finger and fall out of the magazine. Such unintended discharge of one or more of the corner protectors is disruptive with respect to operation of the wrapping or strapping apparatus and, additionally, requires removal of the corner protectors from the area at the discharge end of the magazine and discarding thereof as unusable. Still further, the articulated arm arrangement by which a corner protector is removed from the magazine and transferred to the corresponding corner of the load is likewise structurally complex requiring mechanisms for pivoting one portion of the arm about one axis and the entire arm about a second axis in order to appropriately position the inner sides of the corner protector relative to the corner of the load. This undesirably adds to the expense of the construction of the apparatus as well as to the maintenance and operation thereof.
Top protectors are also made of paper or paperboard material, and top protector applicators heretofore provided generally include a shuttle mechanism carrying a pick-up and transfer assembly by which a flat top protector is picked-up from a supply station and transferred to a position on top of the load. The pick-up and transfer assembly includes fingers by which marginal edge portions of the top protector are bent downwardly to overlie the upper ends of the sides of the load. Heretofore, the fingers by which the marginal edge portions of the top protector are folded downwardly are pivotal about axes parallel to the top edges of the load and laterally or horizontally fixed relative thereto. Accordingly, a different folding finger assembly has to be provided for each load having different top edge dimensions. In this respect, a finger assembly in which the pivot axes are laterally spaced apart a fixed distance cannot be operated to appropriately fold the marginal edge portions of a top protector for a load in which the opposed parallel side edges of the top are spaced apart a distance either greater than or less than the fixed distance between the finger axes. In this respect, if the load edges are spaced apart a distance less than the distance between the finger axes, the fingers cannot pivot to fold the marginal edge portions of the top protector, and if the load edges are spaced apart a distance greater than the distance between the finger axes, the fingers can only partially fold the marginal edge portions downwardly and cannot displace the latter into facial engagement with the sides of the load. Having to provide different finger assemblies for different sized loads is expensive from the standpoint of having to construct a plurality of finger assemblies and from the standpoint of the time required to remove one assembly and replace it with another.